Fix shader support of OVR_multiview

Fix up incorrect capitalization of gl_ViewID_OVR in a few places.

Also add extension macro test to compiler unit tests.

BUG=angleproject:1669
TEST=angle_unittests

Change-Id: Ia7fdd747ad08355cdc149db9e2e7911c2e673af5
Reviewed-on: https://chromium-review.googlesource.com/425851
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>
diff --git a/src/compiler/translator/OutputGLSLBase.cpp b/src/compiler/translator/OutputGLSLBase.cpp
index e7684ed..18afc83 100644
--- a/src/compiler/translator/OutputGLSLBase.cpp
+++ b/src/compiler/translator/OutputGLSLBase.cpp
@@ -1143,7 +1143,7 @@
         if (mCompileOptions & SH_TRANSLATE_VIEWID_OVR_TO_UNIFORM &&
             name.getString() == "gl_ViewID_OVR")
         {
-            TName uniformName(TString("ViewId_OVR"));
+            TName uniformName(TString("ViewID_OVR"));
             uniformName.setInternal(true);
             return hashName(uniformName);
         }